From: Johannes Schindelin <johannes.schindelin@gmx.de>

The SOCKS proxy test introduced in 0ca365c2ed4 (http: do not ignore proxy path, 2024-08-02) creates a Unix domain socket in `$TRASH_DIRECTORY`. When the trash directory path is long (e.g. when running from a deeply nested worktree), the socket path can exceed the 108-character limit for `struct sockaddr_un.sun_path` on Linux, causing the test to fail with "Path length ... is longer than maximum supported length (108)".

Move the socket to `$TMPDIR` (defaulting to `/tmp`) where the path is short, following the same approach used in t7528 for the SSH agent socket in b7fb2194b96 (t7528: work around ETOOMANY in OpenSSH 10.1 and newer, 2025-10-23).

Assisted-by: Claude Opus 4.6
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
    t5564: use a short path for the SOCKS proxy socket
    
    When trying to run the entire test suite in a slightly deeper path than
    usual, I was surprised to see that this test failed due to our old
    friend, the 108 character limit of Unix sockets.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-2100%2Fdscho%2Favoid-too-long-unix-socket-path-in-socks-proxy-test-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2100/dscho/avoid-too-long-unix-socket-path-in-socks-proxy-test-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/2100

 t/t5564-http-proxy.sh | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

On Mon, Apr 27, 2026 at 02:21:09PM +0000, Johannes Schindelin via GitGitGadget wrote:

OK. We try to work around this with a chdir in our own socket code, but I guess we're not using it here:

  1. The socket is created by our socks4-proxy.pl script, which just
     feeds it to perl's IO::Socket::UNIX. And it looks like it
     recognizes the long path and complains. We could fix that, but...

  2. The reading side is implemented by libcurl, not by us. And it seems
     to similarly detect and complain. We _could_ work around that with
     a chdir, but it would be quite nasty, as we'd have to do it before
     every curl call. So that's probably off the table.

And so we are stuck with either using a relative path, or a known-small one.

OK, there we went with the known-small solution, since openssh made it easy to do so. I think that is OK here, but...

This is a static path in /tmp, so:

  1. Multiple instances of the test suite will stomp on each other
     (e.g., a --stress run).

  2. It creates a tmpdir-race vulnerability if an attacker links that
     path to something precious writeable by the user running the tests.

I think it would be sufficient to use mktemp to get a unique name. We don't want a file, of course, so we perhaps need "mktemp -d" to get a temp directory, and then we can use whatever short name we like inside it.

And the rest of your path can remain as-is, since SOCKS_SOCK will have the unique name in it.

-Peff

From: Johannes Schindelin <johannes.schindelin@gmx.de>

The SOCKS proxy test introduced in 0ca365c2ed4 (http: do not ignore proxy path, 2024-08-02) creates a Unix domain socket in `$TRASH_DIRECTORY`. When the trash directory path is long (e.g. when running from a deeply nested worktree), the socket path can exceed the 108-character limit for `struct sockaddr_un.sun_path` on Linux, causing the test to fail with "Path length ... is longer than maximum supported length (108)".

We cannot work around this using the chdir trick our own socket code employs, because both sides of the connection are outside our control: the socket is created by socks4-proxy.pl via Perl's IO::Socket::UNIX, and the client side is libcurl.

Use `mktemp -d` to create a unique temporary directory with a short path, and place the socket inside it. This avoids collisions between concurrent test runs (e.g. `--stress`) and tmpdir-race vulnerabilities that a static `/tmp` path would be susceptible to.

Helped-by: Jeff King <peff@peff.net>
Assisted-by: Claude Opus 4.6
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
    t5564: use a short path for the SOCKS proxy socket
    
    When trying to run the entire test suite in a slightly deeper path than
    usual, I was surprised to see that this test failed due to our old
    friend, the 108 character limit of Unix sockets.
    
    Changes since v1:
    
     * Uses mktemp -d now, to handle --stress better (thanks, Jeff!)

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-2100%2Fdscho%2Favoid-too-long-unix-socket-path-in-socks-proxy-test-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2100/dscho/avoid-too-long-unix-socket-path-in-socks-proxy-test-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/2100

Range-diff vs v1:

 1:  16826e612c ! 1:  256b76a999 t5564: use a short path for the SOCKS proxy socket
     @@ Commit message
          Linux, causing the test to fail with "Path length ... is longer
          than maximum supported length (108)".
      
     -    Move the socket to `$TMPDIR` (defaulting to `/tmp`) where the path
     -    is short, following the same approach used in t7528 for the SSH
     -    agent socket in b7fb2194b96 (t7528: work around ETOOMANY in OpenSSH
     -    10.1 and newer, 2025-10-23).
     +    We cannot work around this using the chdir trick our own socket code
     +    employs, because both sides of the connection are outside our control:
     +    the socket is created by socks4-proxy.pl via Perl's IO::Socket::UNIX,
     +    and the client side is libcurl.
      
     +    Use `mktemp -d` to create a unique temporary directory with a short
     +    path, and place the socket inside it. This avoids collisions between
     +    concurrent test runs (e.g. `--stress`) and tmpdir-race vulnerabilities
     +    that a static `/tmp` path would be susceptible to.
     +
     +    Helped-by: Jeff King <peff@peff.net>
          Assisted-by: Claude Opus 4.6
          Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
      
     @@ t/t5564-http-proxy.sh: start_socks() {
       # proxy string passed to curl.
      +# Use a short path for the socket to avoid exceeding the 108-character
      +# Unix domain socket limit when the trash directory path is long.
     -+SOCKS_SOCK="${TMPDIR:-/tmp}/git-test-socks-%30.sock"
     ++SOCKS_TMPDIR=$(mktemp -d)
     ++SOCKS_SOCK="$SOCKS_TMPDIR/%30.sock"
      +
       test_lazy_prereq SOCKS_PROXY '
       	test_have_prereq PERL &&
     @@ t/t5564-http-proxy.sh: start_socks() {
       test_atexit '
       	test ! -e "$TRASH_DIRECTORY/socks.pid" ||
       	kill "$(cat "$TRASH_DIRECTORY/socks.pid")"
     -+	rm -f "$SOCKS_SOCK"
     ++	rm -rf "$SOCKS_TMPDIR"
       '
       
       # The below tests morally ought to be gated on a prerequisite that Git is

 t/t5564-http-proxy.sh | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

On Wed, Apr 29, 2026 at 08:22:54AM +0000, Johannes Schindelin via GitGitGadget wrote:

Thanks, this looks great to me (and thank you for fleshing out the explanation in the commit message, too).

-Peff